Methods and apparatus are known for forming, filling and sealing bags formed from a continuous sheet of material. In conventional apparatus, a folded sheet of vertically disposed material is advanced longitudinally and heat sealed to form a bag, or pouch, which is gravitationally loaded by means of a declining chute connected to an elevated hopper. After the bag has been formed and loaded, its upper end is seamed to completely seal the bag. The thus filled bag is subsequently severed from the web. Machines of this general nature are disclosed in the following U.S. Pat. Nos.: 2,334,256; 2,385,229; 3,426,499; 3,731,451; 3,815,318; 4,144,693; 4,235,064; 4,322,929; and 4,391,081. Other types of packaging machines are disclosed in U.S. Pat. Nos. 3,319,538 and 3,397,505. Related types of commercially available packaging machines are sold by Rennco, Inc. of Homer, Mich.; Automated Packaging Systems, Inc. of Twinsburg, Ohio; and Bodolay-Pratt of Lakeland, Fla.
A limiting factor in the reliability of a plastic bag forming a filling machine resides in the means utilized to separate the filled bag from the web from which it is formed. Known machines use knives, hot wires, and the like to effect separation. These separating mechanisms are undesirable, however, because the plastic accumulates thereon and causes them to malfunction. As a result, the machinery must be stopped periodically and cleared.
Another acute problem is caused by the composition and quality of the plastic composing the web. For instance, when hot knives and wires are used as the bag separating means, their proper functioning is dependent on the composition and quality of the plastic, since different plastic materials, and variations in quality with a given roll of plastic, change the heat requirements needed to effect proper bag separation. This creastes further machine set-up and operating problems. In addition, the burning of the material by the hot wires causes undesirable fumes to be generated, and this is unsatisfactory.
While each of the aforedescribed patented and commercially available machines may function satisfactorily for its intended purpose, there is a need for machinery which can operate in a reliable method with minimal maintenance to form, fill and seal bags made from a continuous web of plastic at relatively high rates of production. Furthermore, there is a need for a machine of the aforedescribed type which is tolerant of variations in plastic composition and quality and which can operate with a minimum of downtime and with a minimum of operator adjustments. Moreover, a commercially-desirable machine should also be capable of being run by a relatively unskilled operator.